What I mean is, is there a past, future and present? or just a NOW which changes?

I'm a computer programmer so the second alternative is from my programming experience. In this second alternative, I mean to ask, are we just in a stateful system like Conways game of life where there is just a NOW and then the system updates and then we are in a different NOW. In the conways game of life, there is never any past stored in the computer memory. In this case, the past is just an illusion from us recording events which have happened in our brain.

There is a distinct difference between the two, if there is actually a past, future and present then there is opportunity for things in the future to affect things in the past or time-travel might be possible. However in a stateful system like the game of life, then that really cannot happen.

Secondly, do any experiments confirm or deny either of these two options, is this already a decided problem in physics?

A system with a "real" (real as I describe) past, present and future could allow for travel in the time dimension just as you would travel in the x,y or z dimension. One person could travel slowly backwards in time to a point in the past, then move forward slowly and see events as they happen slowly. Not everyone is moving "forwards" together like in conways game of life. In a conways game of life, everyone is moving forwards.

In a system with a real time dimension, potentially a person could make a machine to move backwards, which you cannot do in conways game of life, you cannot move backwards to the older state, you cannot see time in reverse as well which you would see if you moved backwards as you would with a film playing backwards or sound recording playing backwards.

The rules of the conways game of life wouldn't permit travelling backwards, so there's no real time dimension to it, only a collective NOW.

The distinction between a system with a real time dimension (as I describe) would be that you can move forwards or backwards in the time dimension.

In a world without a real time dimension there is only conways game of life where everyone is moving forward and there is only a NOW at all times.

Now you could say that the system which I described with a real time dimension could be simulated by a suitable conways game of life, a suitable rules based system, but I think that you could make a distinction between the two, just as you can determine there is a real x dimension in 3 dimension space which is not a result of a conways game of life in the x dimension.

So my question is, is there a real time dimension or is there just a now that everyone is at all the time?

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Actually, Phil, this is not a topic addressed by physics in part because there is not any observable difference between the two interpretations. A "stateful system" can simulate time travel just as well as if there is "actually" a past, present, and future, for example. You might have better luck taking this question to Philosophy.
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David Z♦Dec 13 '11 at 10:00

how can time travel be possible in the stateful system I described? If someone time travelled backwards in time, although they are in a different "state", the people he left behind in the future are still going on with their lives. In this case, it is different to the stateful system I described.
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PhilDec 13 '11 at 13:28

I mean, the stateful system I described cannot do time travel because it cannot go backwards according to the rules. ... well, I see a difference between the two systems. I had hoped others would see a difference.
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PhilDec 13 '11 at 13:59

I think its amazing that this is seen as a physics question physics.stackexchange.com/q/2605 which I would consider a biology question, but this question is not.
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PhilDec 13 '11 at 14:17

If you can propose an experiment which would distinguish between your two interpretations, that would be a first step toward making this a physics question.
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David Z♦Dec 13 '11 at 15:02